obviously whoever turned you onto a loop forgot to tell you that you are supposed to change the loop with a new one about every 60 to 100 arrow shots. this practice will generally prevent any failures.
Like Rick James and gibblet said it should last a couple of thousand shots. Depending on how much weight you pull, how often you shoot, twoloops should last about the life of a string. With a hunting bow either way I would get it replaced along with the string at least once a year. Do it a few months before the season starts to make sure you have time to dial everything in.